1. Field of Invention
At least one embodiment of the invention relates generally to a method and system for providing uninterruptible, regulated power to critical and/or sensitive loads. More specifically, at least one embodiment of the invention relates to the reduction of losses in an uninterruptible power supply due to an automatic voltage regulation transformer.
2. Discussion of Related Art
The use of an uninterruptible power system (UPS) to provide power to a critical load is known. Known uninterruptible power systems include on-line UPS's, off-line UPS's, line interactive UPS's as well as others. On-line UPS's provide conditioned AC power as well as back-up AC power upon interruption of a primary source of AC power. Off-line UPS's typically do not provide conditioning of input AC power, but do provide back-up AC power upon interruption of the primary AC power source. Line interactive UPS's are similar to off-line and on-line UPS's in that they still switch to battery power when a blackout occurs; however, when a power line sag or swell occurs, at least one type of line interactive UPS activates a tap switching voltage regulation circuit to stabilize the output voltage continuously, without consuming battery power. This allows equipment connected to the UPS to continue to operate through extended power line sags or swells without draining the battery. The tap switching voltage regulation circuit often includes an automatic voltage regulation (AVR) transformer.